Help! Fin Rot Vs Fin Damage

Hi all! I have a curious and active betta named Watson, who has either fin rot or fin damage!
He was in a smaller tank initially and I assumed he got fin rot on his back fin when I let the water go a little. That was several weeks ago. Still learning. Anyway, he's been upgraded to a 3 gallonwith frequent water changes and his back fin did not seem to get any worse. Just now I was watching him goof off and realized his anal fin was torn (could have sworn it was fine earlier today). He has a filter in his new set up and has been enjoying playing and exploring around it, as well as surfing the current. He also has a vase tank decoration he likes to swim in. He is very exploratory and active! So, from the pictures- is it fin rot or damage? Thanks!!!!

It looks very much like tail biting, and actually bettas cannot have melafix as a treatment because of their labryinth organ (from what I`ve read on multiple sources), so best to avoid it. You could add bettafix, it`s basically diluted melafix for bettas but it only does slight work for example my betta slightly (more of a scrape) cut himself on a plant and it only really prevented infections. For tail biters you just need to change stuff up every once and a while, for mine I change his around with water changes, (move around decor or replace it every so often) and it keeps him busy from biting his tail! I hope this helps!